Conventionally, in a print system including a host computer (host PC) and a printer, the host PC and the printer are interconnected via a cable, and status information indicating various printer statuses including error information, residual ink amount, battery capacity and the like are relayed to the host PC (for example, Related Art 1: Japanese Patent Application Laid-Open No. 2004-050726).
In this print system, the host PC transmits a status information acquisition command to the printer, and the type of desired status information has been previously registered in the printer. When the status information of the registered type changes, it is updated, and the status information of the type registered by the host PC is read by polling. Further, in recent years, proposed is a print system where all the status information can be arbitrarily transmitted from the printer side to the host PC without transmission of a status information acquisition command.
Today, as one radio data communication system, Bluetooth communication adopting spread spectrum communication in a frequency band of 2.4 GHz is utilized.
In Bluetooth communication, the profiles are determined in correspondence with the respective use cases, and communication control is performed in accordance with each profile. In Hardcopy Cable Replacement Profile (hereinbelow, “HCRP”) as one of the profiles, the method related to communication between a host PC and a printer or scanner is defined in detail. In the HCRP profile, communication is performed through the Logical Link Control and Adaptation Protocol (hereinbelow, “L2CAP”) layer of the Bluetooth communication. A unique 48-bit Bluetooth device address (hereinbelow, “BD_ADDR”) is allocated to a Bluetooth communication device, and upon connection, the BD_ADDR is notified for link connection.
In the HCRP profile, two channels are provided in the L2CAP layer. The host PC transmits communication data on a data channel, and performs various controls on a control channel. In the print system, upon data flow control on the data channel, for example, the number of data bytes receivable by its device (printer) on the control channel is provided as credit to the communication opposite-end device (host PC). The communication opposite-end device transmits communication data through the data channel within a range of the given credit. Further, on the control channel, the device ID of the printer can be received.
Next, a method for acquisition of status information between the host PC and the printer will be described. Note that when the printer and the host PC are interconnected by the HCRP, to display the current status of the printer on the host PC side, the status information can be transmitted from the printer through the data channel. However, there is a device which cannot normally receive printer status information in accordance with specification of protocol stack software.
A printer driver installed in the host PC side determines whether or not the printer status information can be received with the utilized protocol stack. If the printer driver determines that the printer status information can be received, the printer driver transmits a status information command through the data channel to the printer to register desired status information on the printer side. On the other hand, the printer side checks its current status in accordance with the received status information command, and transmits the status including error information, residual ink amount, battery capacity and the like in a predetermined format, based on the registered status information, on the data channel. To notify a user of the printer status, the host PC side displays information on a monitor or the like accompanying the host PC based on the received status information.
Further, when the printer driver determines that the printer status information cannot be received with the protocol stack utilized in the host PC, the printer driver does not transmit the status information command to receive the printer status information.
Note that in a case where data communication is performed using the Bluetooth communication, to prevent occupation of radio communication band, or to prevent electric current consumption, otherwise, due to the specification problem of limitation of simultaneous connection i.e. up to seven devices to one master, link connection and disconnection are performed by one data transmission. In an HCRP print system, link connection and disconnection are performed for one print job. As the status information acquisition command is a sort of print job, upon each transmission of status information acquisition command from the host PC, link connection and disconnection are performed unless the link is already established during printing or the like.
As described above, as some devices cannot perform two-way communication in accordance with a connection opposite-end host PC, when status information is transmitted without discretion from a printer side to such device incapable of two-way communication, a trouble may occur on the communication opposite-end device.
Accordingly, a host PC capable of two-way communication transmits the status information command upon each link connection and performs two-way communication. To always check the printer status and release the printer to be utilized by other devices, it is necessary to prepare a process to establish link connection at predetermined periods, transmit the status information command during the link connection, and receive the status information data.
Further, when the Bluetooth communication is used, as link connection and disconnection are performed by each print job, the printer clears the status type registered upon connection. Accordingly, the host PC transmits the status information acquisition command upon each connection with the printer to obtain the printer status information. For example, even when the host PC monitors the printer status without performing print processing, the host PC transmits the status information acquisition command.
In a printer having plural interfaces in which an interface occupation status is changed in accordance with data communication from a host PC, in a case where data communication from the host PC is performed upon each connection, the interface occupation status is inconveniently temporarily changed.
Further, as in the case of recent cable-connection print systems, the arbitrary transmission of all the status information from the printer side to the host PC without status information acquisition command may be applied to the Bluetooth communication. In this case, it is necessary to operate a driver which always normally receives status information in the host PC. However, the printer is not always connected to such host PC. When application software or driver, which cannot receive status information, operates in a host PC, the host PC transmits data that the printer cannot interpret, and a trouble may occur in the host PC.